Continuity Tester

In issue #1 of the Homebrewer magazine (summer of 2004 published by the AMQRP), Joe Everhart, N2CX,
reported on a continuity tester that his friend Tony, WA3CAO, uses. A friend of mine, Terry, WA0ITP,
made one and I was quite impressed so I made one too. Below is a picture of the outside and one of the inside. This
sits on my work bench and is in use frequently. I like to build little manhattan style projects
and this is a jewel for testing the continuity as you build to make sure you have good conductive
connections. Because of the containers Terry and I have put them in, he calls his
The Spaghetti Tester because spaghetti came in it and I call mine The Philly Tester.

What makes this such a great little tester is:

The circuit draws no current unless it is testing something

The tone it produces varies in pitch with the resistance under test. The higher the tone the lower the resistance.
It even tests electrolytic
caps.

It only sends one mil of current through what is being tested so it is safe to use on almost anything.